Last week, I presented a situation that Outlook support personnel see frequently-a user migrates to a new system but can't get their Outlook contacts into an address book. Most likely, you just need to identify the contact folder (in the Navigation Pane) as an address book as follows:

Right-click the folder and choose Properties

Click the Outlook Address Book tab.

Check the Show This Folder As An E-mail Address Book option.

Change the folder's name if you like (but this step isn't necessary).

Click OK.

Thanks to DarkGuardian for playing along and offering the correct solution!